In the electronic equipment and telecommunications industries there is a wide-spread need to make electrical connections between components, often on a small scale. For instance, it is necessary to make electrical connections between printed circuit boards or liquid crystal displays by connecting an array of closely-spaced, side-by-side pads, on each respective component. Electronic components are often arranged in computers or the like with extreme space restrictions. Therefore, it is often necessary for the electrical connectors to be flexible. Accordingly, flexible conductive tapes having closely spaced parallel, conductive stripes, that extend the entire length of a flexible insulated support, are in widespread use in the electronic equipment and telecommunications industries.
Known conductive tapes include conductive stripes consisting of: (a) conductive inks, (b) thin metal wires, or (c) stripes of thin metal films, e.g., deposited through a mask or selectively etched to provide the desired conductor width and spacing. Thin metal stripes, are typically covered with an anisotropic conductive adhesive to electrically connect the conductive stripes to an array of terminal pads on a printed circuit board, liquid crystal display, or the like.
There are disadvantages inherent in each of the three presently known conductive tape constructions. Conductive tapes that use conductive inks as the conductive stripes typically have a undesirably high resistance. The manufacture of conductive tapes using thin metal wires for the conductive stripes requires drawing the metal wires down to size and attaching the wires to a flexible insulating support. Known methods are typically difficult and expensive. Production of thin metal films usually requires vapor deposition. The stripes are made by either masking during vacuum deposition or by selectively etching the metal films after deposition, for example, by means of photolithographic techniques. The rate at which metal films are deposited in vacuum metalization processes often makes it economically unattractive to increase the thickness of the metal stripes to a thickness sufficient to provide the desired low resistance pathways.
In presently known electrical conductor tapes, the conductor tape is often constructed such that the spacing of the individual conductive stripes is the same as that of the terminal pads to which it is intended to be bonded. Accordingly, when the bonds are made between the conductive stripes and an array of terminal pads, it is necessary that absolute registration be maintained between the stripes and the pads during bonding. The fine pitch of many arrays of terminal pads makes such registration very difficult. Thus, it is often necessary to use magnifying devices when bonding the conductive tape to the terminals. However, if the pitch of the electrical conductors is so fine that one or more conductors will contact a terminal pad during bonding, absolute registration will not be necessary. It will still be necessary, in most applications, to maintain a generally parallel alignment to prevent cross-over connections.
Therefore, there is a need for a universal, flexible, conductive connector tape, adapted to provide electrical connection between two arrays of closely-spaced conductive pads. There is also a need for a connector tape with a plurality of conductors, regularly-spaced longitudinally in the conductive tape, having a sufficiently fine pitch so that absolute registration is not necessary in most applications. There is a further need for a conductive tape which provides low resistance paths, bonds firmly to an array of terminal pads, and is relatively simple and economical to manufacture. There is a further need for a method by which various connector tape constructions can be made, that are adapted to bond to an array of terminal pads by means of adhesive, conductive-adhesive, and/or solder bonds.